This invention relates to connection admission controlling system and method in an ATM (asynchronous transfer mode) network, and more particularly, to connection admission controlling system and method which are based on measuring a traffic of a call.
Description of the Related Art
The connection admission controlling system in an ATM network prevents admission of a call which can not be accommodated in the network. Thereby, the connection admission controlling system prevents deterioration of communication quality. The connection admission controlling system needs capacities for maintaining the communication quality, for efficiently utilizing resources of the network, and for carrying out, at a real time and at a high speed, process of connection admission of the call. The connection admission controlling system generally approximates a real traffic to a traffic model which is previously set in response to a traffic descriptor which is proposed by a user by use of a calling station when the call is received. Thereby, the connection admission controlling system carries out appreciation of such as the communication quality to make a judging reference for reception of the call.
In the manner which will be described more in detail, a conventional connection admission controlling system is supplied with a traffic descriptor having an average rate and a peak rate of a traffic of a call. The traffic descriptor is included in a connectivity restriction of a connectivity cell from one of calling stations. The average rate and the peak rate are proposed by a user by use of the calling station. The conventional connection admission controlling system judges whether or not a call is required, namely, whether or not the connection admission controlling system is supplied with the connectivity restriction of the connectivity cell from the one of calling stations. When the connection admission controlling system is supplied with the connectivity restriction of the connectivity cell, the connection admission controlling system computes a necessary bandwidth of the call by using a predetermined computing method which computes the necessary bandwidth of the call in response to the average rate and the peak rate which are proposed. The connection admission controlling system judges whether or not the call is admitted in response to the necessary bandwidth.
However, it is difficult that the user previously knows the traffic descriptor. Also, there is a problem that the traffic descriptor proposed has an unstable reliability.
Another conventional connection admission controlling system is disclosed in Japanese Unexamined Patent Prepublication (kokai) No. 167608/1993. The conventional connection admission controlling system controls connection admission in response to the traffic descriptor and measurement of the traffic. The conventional connection admission controlling system is applied to a network of bufferless models that do not have a buffer. However, the conventional connection admission controlling system is not applied to many networks which have buffers and which presently are used.
In conventional connection admission controlling systems, since the systems generally approximate real traffics to traffic models, the systems do not have capacities for maintaining the communication quality, and for efficiently utilizing resources of the network when the systems are supplied with calls which have many different traffic cahracteristics.